Electronic typewriters have always had the capability of storing operator designated tab stops to provide fixed locations relative to the page which the operator may quickly access through the use of the tabulation key on the keyboard. This storage of the tab stop location is typically in a segment of the memory which is designated the electronic tab rack or the electronic tab storage. The storing of the tab stop location in the electronic tab storage may take the form of a value which represents the distance onto the page along a horizontal writing line to the desired position. This distance is measurable from a base point. One such typical base point is the left limit of travel of the print point, usually defined by the left frame of the typewriter or other fixed obstruction to further leftward movement of the print carrier and the print point. An alternative approach is to store in the text memory a tab code and a value representative of the distance from the left margin to the tab stop. This value is derived from the print point position, the tab stop position in the electronic tab storage and the left margin position.
Both of these approaches are embodied in typewriters in the market presently, and each has advantages and disadvantages. The shortcoming of typewriters is that the typewriter is designed to use only one of the approaches, and the advantages of both systems cannot be had in the same typewriter. Particularly, a document which is entered or keyed and stored using one of these approaches cannot be played from storage using the other approach, without getting results that are either undesirable or unpredictable. Thus the ability to reformat a document is limited. For example, in a document created using one approach, margins cannot be easily changed since changing the margins will shift all tab stops that are based on the margin position.
This invention overcomes the problems of entering the document in a first format and then subsequently changing the tab stop layout.